Ultrasonic measurement is an established technique for many industrial applications, such as in medical imaging, materials testing, flow detection and level measurements. The ultrasonic technique has advantages over many existing methods because it is a noninvasive and nondestructive measurement of systems which are concentrated, optically opaque and electrically nonconducting. The primary limitation of this ultrasonic measurement technique has been in its use of its ultrasonic transducers which cannot operate in high temperature and high pressure environments. Some known ultrasonic measurement techniques are briefly discussed in the following paragraphs.
U.S. Pat. No. 4,580,444 to Abts et al. discloses an ultrasonic technique to determine the concentration of oil droplets in an oil recovery system by detecting the forward scattering of ultrasonic energy from oil droplets in the oil recovery system. This technique can only be used under ambient conditions and cannot be used at elevated temperatures and pressures.
U.S. Pat. No. 4,527,420 to Foote et al. discloses a method of identifying and determining the size of particulates in a flowing fluid comprising detecting the portion of an ultrasonic pulse scattered from particulates at a preselected angle, converting the results into density and elasticity-related values, and comparing the values with measured or computed values for known particulates. This method also can only be used under ambient conditions.
U.S. Pat. Nos. 4,770,042 and 4,770,043 to Cobb et al. disclose an apparatus for monitoring the suspension stability in a slurry. This apparatus is limited to use under ambient conditions.
U.S. Pat. No. 5,058,432 to Morkun et al. discloses a method for measuring parameters of solid phase slurries. This approach can only be used under ambient conditions.
The present invention overcomes these limitations of the prior art by positioning ultrasonic transducers outside of the high temperature and high pressure environment of the material being analyzed, while allowing for transmission of ultrasonic waves through the material for analysis of its concentration and particle size distribution. The ultrasonic measurement approach of the present invention is adapted for use in measuring the solid and gas concentrations in an autoclave reactor at elevated temperatures and pressures.